1. Field of the Invention
The present invention relates to circuit boards used in electronic apparatuses and to mounting structures including the circuit board which electronic components such as various audio visual apparatuses, electric household appliances, communication devices, computer apparatuses and peripheral devices thereof are mounted on or embedded in.
2. Description of the Related Art
Circuit boards which electronic components are mounted on or embedded in have been known. Such electronic components include semiconductor elements, capacitors, and the like. The semiconductor elements include IC (integrated circuit), LSI (large scale integration), and the like.
Japanese Unexamined Patent Application Publication No. 9-23065 discloses a circuit board including an insulating layer containing a resin and a conductive layer formed on the insulating layer and containing a metal.
An electronic component and a circuit board have different coefficients of thermal expansion. Therefore, for example, when heat is applied to the circuit board due to heating in solder ref lowing for mounting an electronic component or heat generated by an electronic component, a difference in the amount of thermal expansion occurs between the electronic component and the circuit board. Consequently, heat stress is applied between the insulating layer and the conductive layer, thereby separating between the insulating layer and the conductive layer and decreasing the reliability of the circuit board.